[R] Substring function?

[Nikhil Kaza]

well %in% is really checking if the element is in the set and is not a  
substring operator.

To get the result you want, try

content[grepl(search$signatures, content$urls),]

For multiple operations you could try

sapply(search$signatures, grepl, x=content$urls)




Nikhil Kaza
Asst. Professor,
City and Regional Planning
University of North Carolina

nikhil.list at gmail.com

On Jul 13, 2010, at 8:22 AM, Ralf B wrote:

> Hi all,
>
> I would like to detect all strings in the vector 'content' that
> contain the strings from the vector 'search'. Here a code example:
>
> content <- data.frame(urls=c(
> 					"http://www.google.com/search?source=ig&hl=en&rlz=&=&q=stuff&aq=f&aqi=g10&aql=&oq=&gs_rfai=CrrIS3 
> ",
> 					"http://search.yahoo.com/search;_ylt=Atvki9MVpnxuEcPmXLEWgMqbvZx4?p=stuff&toggle=1 
> ")
> )
> search <- data.frame(signatures=c("http://www.google.com/search"))
> subset(content, search$signatures %in% content$urls)
>
> I am getting an error:
>
> [1] urls
> <0 rows> (or 0-length row.names)
>
>
> What I would like to achieve is the return of
> "http://www.google.com/search?source=ig&hl=en&rlz=&=&q=stuff&aq=f&aqi=g10&aql=&oq=&gs_rfai=CrrIS3 
> ".
> Is that possible? In practice I would like to run this over 1000s of
> strings in 'content' and 100s of strings in 'search'. Could I run into
> performance issues with this approach and, if so, are there better
> ways?
>
> Best,
> Ralf
>
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